Xenogeneic tissue, implant tissue from species different than the implanted species, is useful for replacing human organs damaged by pathological or physical injury. Xenografts are used for replacing heart valves, tendons, skin, blood vessels, ligaments, etc.
Xenografts are treated by several processes for cross-linking the predominate collagen to render the xenografts less susceptible to degradative mechanisms of the human system. Xenografts are preserved in sterile solutions, usually a dilute solution of glutaraldehyde or formaldehyde following treatment, during shippment and awaiting implantation. While the apparatus and methods of this invention are not so limited, the washing of heart valve prostheses will be described to illustrate and exemplify the invention. A typical tissue heart valve prosthesis is made of a porcine heart or of membrane tissue mounted on a stent. The tissue is treated with various reagents to cross-link the collogen, alter the characteristics of the tissue, etc. and is preserved in a glutaraldehyde or formaldehyde or other solution which contains a preservative and/or bacteriostatic compound. For descriptive purposes, glutaraldehyde solutions will be discussed as exemplary, though the particular nature of the solution is not critical to the invention. It is extremely important that all of the glutaraldehyde, formaldehyde or other preservative solutions be removed from the valve before it is implanted in the patient. Some chemical treatments create the risk that some toxic response will be encountered in sensitive individuals, even after general washing of the xenograft prior to implantation. Frolova, M. A.; Barbarash, L. S.; Gudkova, R. G. Carpinskaya, B. M., The Effect of Various Preservation Methods on Immunoqenicity and Antiqenic Composition of Xenoqeneic Valve Tissue of the Heart, Byull. Eksp. Biol. Med., Volume No. 3, 1973, pp. 83-86.
The washing step has been tedious, time consuming and must be accomplished immediately before surgery. The general methods of rinsing the xenograft prior to implantation have not substantially decreased the risk of toxic response by completely removing the preservative. The present invention is designed to provide a system for complete washing of valve and graft tissues with a maximum of efficiency and a minimum of inconvenience and time.